The Midwest and mid-Atlantic regions of the U.S. are at a significant risk of severe weather to start the early weekend with the threat of hail, flash flooding and tornadoes on Friday night, May 16.
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00:00Whenever we talk about severe weather, the one thing that we know about severe weather,
00:05the atmosphere never hides its intentions.
00:08It's like a bullhorn telling you where the general area is going to be, and the ingredients
00:13are always, always the same.
00:16Let's begin with ingredient number one, heat.
00:19And we've got unusual heat, and that's the biggest concern that we've got with this.
00:23Look at this, temperatures in the 80s and 90s across the south here.
00:28This type of heat is more reminiscent of mid-June or early July than it is mid-May.
00:35So we've got unusual heat and humidity just to the south.
00:39That warm, moist air is what's going to feed, it'll be the fuel for these severe thunderstorms.
00:44It's one of the reasons where unusual heat and humidity is why we're concerned about unusually
00:48high risk of damaging winds.
00:50And there's the humidity.
00:51Take a look at our future dew points.
00:52Listen, anything in green is above 60 degrees.
00:55That's the threshold.
00:56You can see some dark green showing up there, 65, 66 from Nashville all the way up into Kentucky.
01:02So we have the warmth.
01:04We have the humidity.
01:05It's unusually warm.
01:07And then think of this as the gasoline.
01:10Let's talk about the match, John.
01:12Yeah, here comes the match.
01:14And this is going to ignite the whole setup.
01:16We have a very potent jet stream disturbance that's going to be racing eastbound at about
01:2120,000 feet in the atmosphere.
01:22And that's going to create lift.
01:23So we've got the fuel in place.
01:26We talked about the warmth and the moisture.
01:28But then this is what ignites it all because it generates lift in the atmosphere to build those tall thunderstorm clouds.
01:35And, you know, you and I both studied at Penn State.
01:37One of our mentors, Dr. Michael Fridge, just an icon in the meteorology ranks.
01:43He always talked about the low-level jet.
01:44The winds are around 5,000 feet.
01:46Not only to diagnose where they're strongest, but are they increasing or decreasing?
01:51And when there's an increasing low-level jet, look out.
01:54Let's take a look at that product, John.
01:55What do you see?
01:56Well, when you and I were studying this this morning, Bernie, the thing that hit us about
02:00it is watch the increase in darker colors across this corridor as you loop this out through
02:05Friday afternoon.
02:06We have wind speeds above 100 and 105 miles per hour at 5,000 feet.
02:11And when you have such high winds at that level in the atmosphere, that's an indication of
02:16the damaging wind potential.
02:18And also, this can impart shear or wind shear or changing wind speed and direction with height
02:24in the atmosphere.
02:25That's the reason why we're concerned about a widely separated tornado risk as well.
02:30Now, we start off in the morning, some morning convection.
02:33Maybe they're wind, maybe they're hailers.
02:35But it's the late afternoon, John.
02:37And watch the cluster of thunderstorms start to develop here as early as 3 o'clock.
02:42What catches our eye about this is how quickly these erupt.
02:46And then they consolidate, Bernie, into clusters of thunderstorms.
02:50And when you get this type of signature here on a simulated, what the radar will look like
02:55this at 9 p.m. central, that's an indication that these storms can have a lot of damaging
02:59wind potential that can down trees, power lines, and lead to widespread power outages.
03:04And then watch how it consolidates through the evening.
03:07There's no rest on this one through the evening and into the overnight.
03:10It keeps hauling eastbound.
03:12A lot of times these clusters of storms can really race eastward and produce a damaging
03:17wind threat over a multi-state area.
03:20We're concerned this could even become a derecho, which is a particularly intense thunderstorm
03:26windstorm with widespread wind damages.
03:28It's the kind of power outages that in some cases could last for days in the hardest hit
03:32areas.
03:33John, really quickly here.
03:34Have we decided to make any changes with our severe weather threat?
03:38We just ended MEP discussion.
03:39Right.
03:40We have AccuWeather experts have a high risk here across parts of the Ohio Valley.
03:44We're the only known source to be talking about it in that way.
03:47The government and other sources do not have that level of high risk that AccuWeather meteorologists
03:51are concerned about.
03:52We think it could be a widespread damaging wind event, as mentioned.
03:55And we're going to be pulling this moderate risk a bit closer to Pittsburgh and also further
03:59south and east here across parts of Tennessee to account for that risk for damaging winds
04:04and widely separated tornadoes.
04:06We're worried about power outages.
04:08We're going to end on this map.
04:09Know what to do.
04:10If you have a downed power line, stay away from them and do get ready.
04:14We are very concerned about widespread power outages in Kentucky, Tennessee, and southern
04:20parts of Illinois and Indiana.
04:22Chief Meteorologist John Porter, thanks for joining us here on AccuWeather Early.
04:26Chief Meteorologist John Porter, thanks for joining us here on AccuWeather.
04:29Chief Meteorologist John Porter, thanks for joining us here on AccuWeather.